Knife cleaner for rotary tobaccoleaf cutting machines



June 6, 1944. H. w. LANGRISH 2,350,685

KNIFE CLEANER FOR ROTARY TOBACCO-LEAF.CUTTING MACHINES Filed Oct. 2 19412 Sheets-Sheet 1 Jung 6, 1944. H. w. LANGRISH 2,350,686

KNIFE CLEANER FOR ROTARY TOBACCO-LEAF CUTTING MACHINES Filed Oct. 2.1941 2 Sheets-Sheet 2 angle is'chosen by experiment to find the best 7for cutting a cheese of the cross-section determined ,1 by. the?particular rnouthpiece. The edge ofeach knife lies in a plane normal tothe axis of rotation of theknife carrier. The edge of each knife maythus be said to be a line on the rotatable head. V w

the method hereinafter described with respect to with that of the knifecarrier shaft 2'. Secured to the shaft I for arcuate-movement therewith(e. g. rotation) is a remover element which' com' I prises a scraper l.The scraper is fixed toa block H which is pivoted at 8 to a lever 9fixed on the shaft, i0 .whichforms the axis of rotation of the. removerelement. of slight movementabout the pin 8again'st the tension of; thespring I 2. The lever-9 may be ro- :tated. in any .convenientmanner butfor simplicity it is, shownas being driven :by, a chain from theshaftlof the knife: carrier. Tothis shaft. there is fixed a sprocketwheell3on which *achain l4 runs; the chain also'passesover a smallsprocket J5 fixed to the spindle l0 about,

vthe axis. of which the element revolves. The operative portion of thescraper is, in one form, of substantially inverted V shapeand at theapex of the- V' thescraper is arranged to engage the knife edge whilegonone side ofthe V it engages the=backof the: knife and on the otherside=of they engages the chamfer on the frontof the knife, all inthemanner to be described here- :after withreference to Figures 3 and 4;

The orbital-path of the knife edge is intersected by the, path. of theapex of the V. and the relative speeds ofthe knife and thescraper andthe distance of each from the axis about which it moves are so chosen.that the trace of the ex- 171'611'18 point of the apex of the Vcoincides with accordance with the invention is shown-in Fig- The blockIi is capable the'flinifeedgeflles atan angle of" 32; with respect tothe radius RI so'that the upper position of the knife edge is easilydrawn in by placing it at an angle of 32 with respect to the radius R2 Aline X--Y drawn through the intersec- At some suitable position to bedetermined by 1 ctions a, n, 0.1 r, m so obtained is an arc of a circle,the radius Z of which can be readily ascer- Figure 2, a second shaft II]is mounted ,forrota-j "taine d by'construction and measurement, thustion, the axis of this second shaft beingl parallel determining theposition for the axis I'll of rotation of the scraper. This are 9, n, o,p, r, m,

is. therefore a trace in space formed by a point 1 fprogressingoutwardly along the line a, g at sucsecond revolution of the knifecarrier.

of the edge, that the ,whole 11.40.

cessivemoments during movement of the rotatable 'knife carrier. This arehaving beenobtained,- the relative angular speeds of the knife .andscraper can be readily calculated once the angular speedof the knifexisknown, since the linear speed of the scraper must equal the speed atwhich the trace is formed. I

, In the machine being described the scraper -rnakes five revolutions totwo of the knife carrierso that each knife is scraped during each Asabove described the arrangement is adapt- I ed' to scrape the entirestraight edge of a knife. 'Since, however, the knife is continuallyground during the operation of the machine by the grinding wheel shownin Figure 1 the edge of the knife is usually notquite straight but isconcave. The extent to which theedgeis not straight is about .005" to..01! between the oppositecorners In some cases it is not. important of;the.edge shall be engaged by the scraper, andjn these. cases moving thescraper over the edge -and, in close...proximity ,thereto willensurelthat no undue accumulation of resinous substanceswillloceurbn theknife. .Whenrhowever, it is desired to. scrape the entire edge in suchcases, the scraper is resiliently mounted on the lever secured to thescraper shaft as described with reference to Figure 1. The

scraper could of course be articulated and arranged to move out .bycentrifugal force against theknife edge to follow. the latter .where itdeviates from a straight line.

ure 2. ,The distanCe through. which it is de-" sired that the knife.shall be, moved during the scraping operation is first selected and asshown on'the diagram, this distance corresponds to the distance betweenthe ends a and m of the radial .lines RI, and R2. The orbital path ofthe knife is, of course, known and asshown the corners of theknifetravel along arcs struck about the axis of; rotation from the points Aand G. The -angular speed at. which'the knife is'moved is -also knownand is constant. A number of equispaced points g to a, respectivelyrepresenting selected positions of a point progressing outwardly alongthe edge are next selected along the knife edge and through these pointsare drawn arcuate linesA to G struck about the axis of rotation-G oftheknifecarrier. ,:These lines pass throughthat part of the orbital pathwithin'which scraping is to be effected. A number of vfines, d n, i, 7,7c,.l, m, equal to the number of.

' It should also be j Similarly if it is not convenientto position theQaxisof rotation of the scraper in its exact posi- ,tion so as to ensurethat it moves along the tracelg, n, 0, 2 L1, m, then thescrapermay beresiliently mounted or arranged to move out'as above-mentioned bycentrifugal force.

a'ppreciatedjthat when it is not necessary that the scrapershall engagethe positions the axis ofrotation of the ensure that the scraper followsthe said trace. Insuch a case, however, it will be understood that thedirection of movement of the scraper would, nevertheless, require to besubstantially straight in order toobtain the requisite scraping effect.I

By frequently engaging the edge of the knife with the scraper in themanner above described, any burrs which tend to form are quicklyremoved.

Referring to Figures 3-11' which show various forms of scrapers and themanner in which they operate to remove materialfrom the rotatable.element, the scrapershown in Figures 3 and I4 is of substantiallyinverted V shape, the apex it of the V being arranged to engage theknife edge as shown in Figure 9 while the side I! of the V engages theback of the knife and part of the clamp while the other side l3 of the Vengages a chamfer on the front of the knife. In Figures 5 and 6 thescraper is only provided with one scraping edge 19 which engages theclamp on the back of the knife as shown in Figure 10. The scraper shownin Figures 7 and 8 is adapted to remove material from the ground face ofthe knife and the neighbouring face of the front portion of the knife,i. e. the face nearer to the cheese of tobacco and part of the frontclamp. This scraper operates in the manner shown in Figur 11. If desiredother shapes of scrapers may be designed to scrape, for example thewhole of the knife and parts of the front and back clamps. This is shownin Fig. 12 where two scrapers are mounted on the block l I, one behindthe other, each scraper dealing with a part of the surface on which theresinous material accumulates, the leading scraper la being that shownin Figures 3, 4, and 9, and the following scraper lb being that shown inFigures '7, 8, and 11.

Although in the examples given, the edge of the knife has beenconsidered as straight or substantially straight and the edge has beenassumed to be regular, the invention could also be applied toconstructions in which the edge whether irregular or regular has partswhich de viate from a straight or substantially straight line to a smallextent. For instance, if in a particular application it sufiiced for theremover element to be at a certain maximum distance, it would clearly bepossible to construct an edge in which there was either irregularity orcurvature to that extent and the words substantially in the direction ofa line and substantially along a trace when used herein and in theclaims mean that the remover element (whether yieldably mounted on acarrier or not) passes along the line or trace at all times within theminimum distance necessary for performing the intended function. Where,however, the remover element is to act as a grinder or hone, it is clearthat the edge of the knife must be a very close approximation to astraight line unless the remover element is yieldably mounted to allowit to compensate for any departure of the knife edge from a straightline. It is to be appreciated, however,

that any such departure from the straight line will be limited byconsideration of expediency.

What I claim as my invention and desire to secure by Letters Patent is:

1. In a tobacco cutting machine, a rotatable knife having asubstantially straight cutting edge inclined to the radial in adirection outwardly and rearwardly with respect to the direction ofrotation and in a plane normal to the axis of rotation, and a scraperblade driven in timed relationship with the knife and shaped to engagethe cutting edge and areas in proximity to the cutting edge of the knifeto remove material therefrom, during movement of the knife, and meanssupporting said blade for movement in a curved path about an axisparallel to and spaced from the knife axis in the same angular directionas the knife and outwardly across the path of the knife in a zonelaterally removed from a line connecting the axes of the knife andblade, means driving said knife and blade in such timed relation thatduring the movement of the blade along the knife, the blade is caused tosweep lengthwise of the whole of said cutting edge with a point on saidblade progressively engaged with successive points on said cutting edge,said sup porting means retaining said blade against axial displacementduring such outward movement.

2. In a tobacco cutting machine, a rotatable knife having asubstantially straight cutting edge inclined to the radial in adirection outwardly and rearwardly with respect to the direction ofrotation and in a plane normal to the axis of rotation, and a scraperblade driven in timed relationship with the knife and shaped to engagethe cutting edge and areas in proximity to the cutting edge of the knifeto remove material therefrom, during movement of the knife, and meanssupporting said knife and blade for rotation on spaced parallel axes andin the same direction, whereby the remover element may move outwardlyacross the path of the knife in a zone laterally removed from a lineconnecting the axes of the knife and blade, means yieldingly supportingsaid blade on said last named means, means driving said knife and bladein such timed relation that during the movement of the blade along theknife, the blade is caused to sweep lengthwise of the whole of saidcutting edge with a point on said blade progressively engaged withsuccessive points on said cutting edge.

HENRY WILLIAM LANGRISH.

